This invention relates in general to model railroad switch tracks or turnouts, to the detection of the position of said turnout movable rails, also called switch points or simply points, the corresponding train route, and to the feedback of the position of said movable rails or points to the model railroad operator and to the model railroad control system. [NOTE: To avoid confusion with an electrical ‘switch’, the term ‘turnout’ will solely be used henceforth to mean a railroad switch or switch track.],
Railroad turnouts, whether on model railroads or real life full-scale railroads, make it possible for trains to follow one out of generally two selectable routes. [NOTE: Henceforth, the term ‘train’ will be used to denote a locomotive, multiple locomotives, railroad cars, or locomotives and cars.]
A railroad turnout includes: a) Fixed stock rails upon which the train wheels run; b) Crossties, which are commonly made of wood and are laid perpendicular to the stock rails, transfer loads to the track ballast and sub grade, hold the rails upright and keep them spaced to the correct gauge; c) Movable, tapered rails, which are anchored at one end and are free to move at the opposite end, called switch points (or just points), and can generally be moved laterally at the free end into one of generally two positions to select the desired route for the trains to follow; d) Connecting rod or throw bar, which connects the free ends of the points and causes them to move in unison; e) And turnout machine, which is attached to the connecting rod or throw bar with a link, and causes said connecting rod or throw bar to move together with the points.
If for any reason the points fail to move to the desired position when the turnout machine is energized with the expectation that it would cause the points to move to said desired position, or if the points move only part way to said desired position, or if the points drift away from said desired position, the train will not follow the desired route or may derail.
In many model railroads, the actual or true position of the points can usually be verified by the model railroad operator through visual inspection of the turnouts and the position of the points. Whether the turnouts are operated manually by the operator moving a lever with his/her hand, or remotely by the actuation of an electrical device that energizes the turnout machine, the points mostly move as intended, and mostly remain in the desired position.
However, regardless of how the turnouts are operated, it is not uncommon for the turnout points to not move to the intended position or to not remain in that position. If the points do not move into the intended position, the train will not follow the intended route; furthermore, if the points drift away from or move only part way to the intended position, a train derailment will likely occur.
In smaller model railroad dioramas, which consist of scale track and associated controls appropriate for operating model trains, which said dioramas are commonly known as model railroad layouts, it is feasible to frequently conduct a visual inspection of the turnouts to verify the actual position of the points. If the railroad operator sees that the points are not fully in the desired position, the operator can actuate the turnout machine again, whether manually or remotely, and visually check to re-verify the position of the points. If the points remain in the incorrect position or not fully into the desired position, the railroad operator can stop the train and correct or repair the problem turnout.
However, in larger model railroad layouts, due simply to the size of the area expanse of said larger layouts, and the number of turnouts involved, it is not feasible to frequently visually inspect all the turnouts and the position of the points to avoid the potential of a wrong route being followed by the trains, or to avert derailments. For these larger model railroad layouts, easily seen indicator display lights placed in close proximity to the turnouts, and/or a control panel with similar indicator display lights, which said indicator display lights reflect the turnout selected routes based on feedback signals from the turnout route detectors, provide a feasible approach to make possible periodic visual inspections of the turnout selected routes by visual assessment of the turnout position indicator display lights. Some model railroad layouts are also operated by computer based control systems, which control systems accept the aforementioned feedback signals from the turnout route detectors, and can automatically perform any required corrective steps based on the nature of the feedback signals.
Unfortunately, the turnout selected route detection methods available, which provide the feedback signals to the indicator display lights and to the control system do not always reflect the actual route. This occurs because said detection methods do not detect or indicate the actual or true position of the points. As a result, the railroad operator and/or the control system may receive an erroneous feedback of the true position of the points, which would preclude the railroad operator or the control system from taking the appropriate corrective action if such were necessary.
The wrong indication or erroneous feedback of the actual position of the points may occur because the commonly available and used turnout route detection methods generally reflect the position of the turnout machine, but not necessarily of the points. In such cases, while the turnout machine may have moved properly and reached the intended position, the connecting rod or throw bar that mechanically links the turnout machine to the points, and the points, may have not moved as intended. Hence, while the feedback signal may correctly indicate the position of the turnout machine, it might not indicate the actual true position of the connecting rod or throw bar and of the points. [NOTE: While the term ‘connecting rod’ is more commonly used in full-scale, real railroads, in model railroading the term ‘throw bar’ is more commonly used, and will be the term used henceforth.]
The above mentioned discrepant indication between the feedback signal and the actual position of the throw bar and points may occur if the throw bar or the points are physically prevented or otherwise blocked from reaching the desired position. Examples of obstacles that can prevent the throw bar and points from reaching the intended position fully include debris, such as a piece of track ballast wedged between the points and the stock rail, and a train stationed over the turnout with one or more of its wheels blocking the movement of the points.
Attempting to use traditional methods of detecting the position of the points in model railroad presents a challenge due to the relatively small size of the turnouts and associated components. These characteristics of model railroad turnouts make it difficult to sense the actual position of the turnout throw bar and points using any sort of mechanical or electromechanical device, such as a limit switch that could be actuated by the throw bar or points, since the sensing device itself would represent an obstacle, and hinder their operation, which could prevent said points from operating properly and reliably. This leaves the generally practical options currently available with existing approaches to generate feedback signals of the selected turnout route, which consist generally of electrical switches of sorts, which are actuated by the turnout machine itself but not by the throw bar or points, or electrical devices that are actuated by the same signals that actuate the turnout machine. Consequently, while these feedback signals may accurately reflect the position of the turnout machine itself, they do not necessarily reflect the actual and true position of the throw bar and points.
The position of the throw bar, and hence the points, may differ from the position of the turnout machine because the linkage between the model railroad turnout machine and the throw bar is intentionally and by design made to be flexible. Although this flexibility hinders a consistent and true correlation of the position of the turnout machine to the throw bar and points, the flexible linkage prevents damage to the turnout machine and its components if the throw bar and points were to be physically blocked from moving to the intended position. In the end, it is more advantageous for the turnout manufacturer as well as to the model railroad enthusiast to forego an accurate correlation of the turnout machine to the throw bar and points, rather than to risk damage to said components.